Thermodynamic signatures in macromolecular interactions involving conformational flexibility.

The energetics of macromolecular interactions are complex, particularly where protein flexibility is involved. Exploiting serendipitous differences in the plasticity of a series of closely related trypsin variants, we analyzed the enthalpic and entropic contributions accompanying interaction with L45K-eglin C. Binding of the four variants show significant differences in released heat, although the affinities vary little, in accordance with the principle of enthalpy-entropy compensation.

Correlating structure and ligand affinity in drug discovery: a cautionary tale involving second shell residues.

A high-resolution crystallographic structure determination of a protein-ligand complex is generally accepted as the 'gold standard' for structure-based drug design, yet the relationship between structure and affinity is neither obvious nor straightforward. Here we analyze the interactions of a series of serine proteinase inhibitors with trypsin variants onto which the ligand-binding site of factor Xa has been grafted. Despite conservative mutations of only two residues not immediately in contact with ligands (second shell residues), significant differences in the affinity profiles of the variants are observed.

High-throughput ptychography using Eiger: scanning X-ray nano-imaging of extended regions.

The smaller pixel size and high frame rate of next-generation photon counting pixel detectors opens new opportunities for the application of X-ray coherent diffractive imaging (CDI). In this manuscript we demonstrate fast image acquisition for ptychography using an Eiger detector. We achieve above 25,000 resolution elements per second, or an effective dwell time of 40 μs per resolution element, when imaging a 500 μm × 290 μm region of an integrated electronic circuit with 41 nm resolution.

Patterns of drought tolerance in major European temperate forest trees: climatic drivers and levels of variability.

The future performance of native tree species under climate change conditions is frequently discussed, since increasingly severe and more frequent drought events are expected to become a major risk for forest ecosystems. To improve our understanding of the drought tolerance of the three common European temperate forest tree species Norway spruce, silver fir and common beech, we tested the influence of climate and tree-specific traits on the inter and intrasite variability in drought responses of these species. Basal area increment data from a large tree-ring network in Southern Germany and Alpine Austria along a climatic cline from warm-dry to cool-wet conditions were used to calculate indices of tolerance to drought events and their variability at the level of individual trees and populations.

Coherent X-ray imaging: bridging the gap between atomic and micro-scale investigations.

We present a review of state-of-the art X-ray imaging techniques based on partially coherent synchrotron radiation. Full-field X-ray tomography, X-ray ptychography, scanning small-angle X-ray scattering, and scanning transmission X-ray microscopy are imaging techniques that gather structural information at spatial resolution ranging from several microns to a few tens of nanometers in both real- and reciprocal space. These methods exploit contrast mechanisms based on absorption, phase, and spectroscopic signals.

Signal amplification and transduction in phytochrome photosensors.

Sensory proteins must relay structural signals from the sensory site over large distances to regulatory output domains. Phytochromes are a major family of red-light-sensing kinases that control diverse cellular functions in plants, bacteria and fungi. Bacterial phytochromes consist of a photosensory core and a carboxy-terminal regulatory domain.

Infrared thermography of the pig thorax: an assessment of selected regions of interest by computed tomographical and anatomical parameters.

Current methods of diagnosis of respiratory diseases in swine are invasive, time-consuming and expensive. Infrared thermography (IRT) of the thorax might provide a new method of high specificity to select swine affected with lung alterations for further diagnostics. In this study, layer thickness of different tissues was determined in frozen thorax slices (FTS) by computed tomography (CT) and then related to skin temperatures measured by IRT in healthy pigs.

Changes in first flowering dates and flowering duration of 232 plant species on the island of Guernsey.

Climate change has affected plant phenology; increasing temperatures are associated with advancing first flowering dates. The impact on flowering duration, however, has rarely been studied. In this study, we analysed first flowering dates and flowering durations from a 27 year dataset of weekly flower observations on 232 plant species from the island of Guernsey in the English Channel.

Experimental observation of defect pair separation triggering phase transitions.

First-order phase transitions typically exhibit a significant hysteresis resulting for instance in boiling retardation and supercooling. The hysteresis arises, because nucleation of the new phase is activated. The free-energy change is positive until the nucleus reaches a critical size beyond which further growth is downhill.

Coherent X-ray Imaging: Bridging the Gap between Atomic and Micro-scale Investigations.

We present a review of state-of-the art X-ray imaging techniques based on partially coherent synchrotron radiation. Full-field X-ray tomography, X-ray ptychography, scanning small-angle X-ray scattering, and scanning transmission X-ray microscopy are imaging techniques that gather structural information at spatial resolution ranging from several microns to a few tens of nanometers in both real- and reciprocal space. These methods exploit contrast mechanisms based on absorption, phase, and spectroscopic signals.

X-ray ptychographic computed tomography at 16 nm isotropic 3D resolution.

X-ray ptychography is a scanning variant of coherent diffractive imaging with the ability to image large fields of view at high resolution. It further allows imaging of non-isolated specimens and can produce quantitative mapping of the electron density distribution in 3D when combined with computed tomography. The method does not require imaging lenses, which makes it dose efficient and suitable to multi-keV X-rays, where efficient photon counting, pixelated detectors are available.

Engineered high aspect ratio vertical nanotubes as a model system for the investigation of catalytic methanol synthesis over Cu/ZnO.

Catalytically synthesized methanol from H2 and CO2 using porous Cu/ZnO aggregates is a promising, carbon neutral, and renewable alternative to replace fossil fuel based transport fuels. However, the absence of surface-engineered model systems to understand and improve the industrial Cu/ZnO catalyst poses a big technological gap in efforts to increase industrial methanol conversion efficiency. In this work, we report a novel process for the fabrication of patterned, vertically aligned high aspect ratio 1D nanostructures on Si that can be used as an engineered model catalyst.

Transient formation of bcc crystals in suspensions of poly(N-isopropylacrylamide)-based microgels.

We present a small-angle x-ray scattering study of crystals formed by temperature-sensitive, swollen microgel particles consisting of poly(N-isopropylacrylamide) copolymerized with acrylic acid and 5 mol % of a cross-linker. As for hard spheres, the random hexagonal close-packed structure is predominant during crystal growth and slowly transforms toward the face-centered-cubic structure. However, a transient phase of body-centered-cubic crystal is observed in an intermediate range of effective volume fractions.

Chilling outweighs photoperiod in preventing precocious spring development.

It is well known that increased spring temperatures cause earlier onset dates of leaf unfolding and flowering. However, a temperature increase in winter may be associated with delayed development when species' chilling requirements are not fulfilled. Furthermore, photosensitivity is supposed to interfere with temperature triggers.

Characterization of elements involved in allosteric light regulation of phosphodiesterase activity by comparison of different functional BlrP1 states.

Bacteria have evolved dedicated signaling mechanisms that enable the integration of a range of environmental stimuli and the accordant modulation of metabolic pathways. One central signaling molecule in bacteria is the second messenger cyclic dimeric GMP (c-di-GMP). Complex regulatory mechanisms for modulating c-di-GMP concentrations have evolved, in line with its importance for maintaining bacterial fitness under changing environmental conditions.

High environmental ozone levels lead to enhanced allergenicity of birch pollen.

Background: Evidence is compelling for a positive correlation between climate change, urbanisation and prevalence of allergic sensitisation and diseases. The reason for this association is not clear to date. Some data point to a pro-allergenic effect of anthropogenic factors on susceptible individuals.

Unidirectional laning and migrating cluster crystals in confined self-propelled particle systems.

One standard approach to describe the collective behaviour of self-propelled particles is the Vicsek model: point-like self-propelled particles tend to align their migration directions to the ones of their nearer neighbours at each time-step. Here we use a variant of the Vicsek model that includes pairwise repulsive interactions. Confining the system between parallel walls can qualitatively change its appearance: a laning state can emerge that is different from the ones previously reported.

Can spatial data substitute temporal data in phenological modelling? A survey using birch flowering.

In addition to the evaluation of long-term series, the analysis of spatial gradients, such as urbanization gradients, may be helpful in assessing phenological responses to global warming. But are phenological responses of birch (Betula pendula Roth) assessed by temperature variations comparable over time and space and can spatially calibrated models predict long-term phenological data adequately? We calibrated and tested linear regression models and the process-based DORMPHOT model on phenological and temperature data sampled along an urbanization gradient in 2010 and 2011 in the German cities Munich and Ingolstadt (spatial data). Additionally, we analysed data from the German Meteorological Service for the period 1991-2010 (long-term data).

X-ray scattering experiments with high-flux X-ray source coupled rapid mixing microchannel device and their potential for high-flux neutron scattering investigations.

Small-angle X-ray scattering provides global, shape-sensitive structural information about macromolecules in solution. Its extension to time dimension in the form of time-resolved SAXS investigations and combination with other time-resolved biophysical methods contributes immensely to the study of protein dynamics. TR-SAXS can also provide unique information about the global structures of transient intermediates during protein dynamics.

Dynamics of a deformable active particle under shear flow.

The motion of a deformable active particle in linear shear flow is explored theoretically. Based on symmetry considerations, we propose coupled nonlinear dynamical equations for the particle position, velocity, deformation, and rotation. In our model, both, passive rotations induced by the shear flow as well as active spinning motions, are taken into account.

Detection of real-time dynamics of drug-target interactions by ultralong nanowalls.

Detecting drug-target interactions in real-time is a powerful approach for drug discovery and analytics. We show here for the first time the ultra fast electrical real-time detection and quantification of antibiotics using a novel biohybrid nanosensor. The biomolecular sensing is performed on ultralong (mm range) high aspect ratio nanowall (50 nm width) surfaces functionalized with operator DNA tetO which is specifically bound by the sensor protein TetR.

Shifting and extension of phenological periods with increasing temperature along elevational transects in southern Bavaria.

The impact of global warming on phenology has been widely studied, and almost consistently advancing spring events have been reported. Especially in alpine regions, an extraordinary rapid warming has been observed in the last decades. However, little is known about phenological phases over the whole vegetation period at high elevations.

Frequency of inversions affects senescence phenology of Acer pseudoplatanus and Fagus sylvatica.

In mountainous regions, inversion situations with cold-air pools in the valleys occur frequently, especially in fall and winter. With the accumulation of inversion days, trees in lower elevations experience lower temperature sums than those in middle elevations. In a two-year observational study, deciduous trees, such as Acer pseudoplatanus and Fagus sylvatica, on altitudinal transects responded in their fall leaf senescence phenology.